Published August 19, 2026 10:36AM<\/p>\n<\/div>\n
Fatigue is a completely normal part of exercising. When you\u2019re training hard, you simply won\u2019t feel fresh and energetic every workout session.<\/p>\n
But athletes throw around the word \u201cfatigue\u201d to mean a whole bunch of things. Maybe your legs feel flat on a run, or maybe you\u2019re struggling with full-body lethargy that sticks around after a cooldown.<\/p>\n
Getting specific about exactly<\/i> what you\u2019re experiencing can offer clues that help you get your pep back\u2014and ultimately improve your running. \u201cFatigue can be a pretty reliable marker of what\u2019s going on under the surface,\u201d says Seattle-based running coach Laura Norris<\/a>, who has a master\u2019s in applied exercise science.<\/p>\n Here are seven types of fatigue that might show up, along with expert advice on how to recover from each.<\/p>\n Some days, it feels like you have no \u201cpop\u201d in your stride\u2014your legs are heavy from the first step of your run or hike to the last, without getting any better after you warm up and stretch.<\/p>\n This is often thanks to too much mileage without enough recovery. You end up losing some of the leg stiffness that puts the spunk in your step, resulting in lower cadence and increased ground contact time, according to Rich Willy, PT, PhD,<\/a> associate professor in the School of Health and Rehabilitation Sciences at The Ohio State University.<\/p>\n Other times, in the case of running, your runs might start to feel flat if you\u2019re doing lots of slower running while skipping speed work. \u201cYou can begin to experience changes in muscle fiber recruitment where you just aren\u2019t recruiting your fast-twitch muscle fibers well,\u201d Norris says.<\/p>\n Cut your run or other outdoor activity short. But if you\u2019re running, you can try<\/em>\u00a0to pick up your cadence. \u201cBut if you\u2019re having a hard time sustaining it, cut your run short and focus on recovery,\u201d Willy says. Trying to power through can overload your knees and hips, potentially leading to injury.<\/p>\n If you think too much easy-paced running could be to blame, Norris recommends spicing things up with some strides or hill strides as a low-stress, low-risk way to get your fast-twitch fibers firing.<\/p>\n When the micro-tears you create in your muscles during a run or hike begin to heal 24 to 48 hours later, you\u2019ll often start to feel what\u2019s called delayed onset muscle soreness, or DOMS. Your muscles might ache just getting out of bed, or you might only feel it once you start moving.<\/p>\n This often happens after you\u2019ve run or hiked longer or harder than you\u2019re used to. However, if you\u2019re chronically sore day after day, it could signal too much volume, too much intensity, or under-fueling, Willy says. A general rule of thumb in training is to only increase one factor at a time; for example, if you\u2019re adding mileage one week, don\u2019t also increase speed.<\/p>\n Prioritize sleep, rest, proper nutrition, and hydration, says exercise physiologist Aashaun Khedaru<\/a>, supervisor of the Sports Performance Center at NYU Langone Orthopedic Center.<\/p>\n If you feel like you\u2019re always<\/i> sore, Willy suggests switching from a seven-day training cycle to a more flexible ten-day cycle to add in more recovery days. And don\u2019t forget to take a recovery week<\/a> every three or four weeks, dialing back your volume by 25-30%. \u201cBone and tendon micro damage take about three weeks to build up to the point where you develop an injury, so if you pull back every third week or so, it gives your physiology a chance to catch up and adapt,\u201d he says.<\/p>\n If you\u2019ve been hiking or climbing, prioritize rest and ensure you\u2019re getting adequate nutrition.<\/p>\n High-intensity runs like speed work can set your muscles on fire. Khedaru explains that this happens because anaerobic metabolism changes the pH levels in your body, making things more acidic. Eventually, that tiring, burning sensation slows you down so you can reintroduce oxygen to your system. \u201cYou start hyperventilating to clear out that waste product until you recover again,\u201d Khedaru says.<\/p>\n The right training can increase how much lactic acid your body can tolerate. Khedaru tells athletes to incorporate active recovery into their interval sessions by slowly jogging between reps. \u201cThat lower-level aerobic work helps your body learn to reconvert that lactate back into fuel,\u201d he says. \u201cOver time, as your body adjusts to that burning feeling, you might be able to push it off for an extra interval or two.\u201d<\/p>\n Suddenly running out of oomph on a long run or race is super common and super frustrating. \u201cYou feel like you want to push, but your muscles can\u2019t do it,\u201d Khedaru says. Your splits get slower (despite putting in the same effort), your cadence tanks, and your form might fall apart.<\/p>\n This is a classic sign of running out of muscle glycogen, which is why run coaches put so much emphasis on proper carb intake. \u201cYour muscles need energy to keep going, and you just can\u2019t provide it anymore because you used all of it,\u201d Khedaru says.<\/p>\n Norris suggests taking a short walk break to reset while getting in some carbohydrates and drinking some water. Then, as long as you can maintain good form, try to start up again. Just know that you may need to settle for a slower pace.<\/p>\n Cumulative stress builds up over the course of a training cycle and can leave you too mentally exhausted to run. Knocking out lots of miles on top of family or work obligations becomes overwhelming rather than an escape. \u201cThere\u2019s a certain level of mental fatigue that takes form,\u201d Khedaru says.<\/p>\n Be kind to yourself. Dial back the volume and find ways to make running fun again. \u201cA missed run here or there is not going to break your entire training cycle,\u201d Khedaru says. That might mean meeting up with friends or a run club, ditching the road for trails, or even swapping\u00a0some recovery runs for bike rides.<\/p>\n You might need time to journal, read, or talk with someone you trust if your mental overload feels like too much to handle.<\/p>\n Although rare, in severe situations, heat exhaustion and dehydration<\/a> can lead to the kind of staggering stride you\u2019ll see in viral videos of marathoners stumbling across the finish line. \u201cThey\u2019re losing their balance. It looks like they\u2019re walking sideways. They really have no control,\u201d Khedaru says. He explains that this is a signature of central fatigue, where your brain is trying to protect your body from further damage by literally forcing you to stop running.<\/p>\n Once your biomechanics fall apart, it\u2019s best to pull the plug on your run or other activity to avoid injury. \u201cStop, get some fluids in, and eat something,\u201d Khedaru says.<\/p>\n If you\u2019re feeling lethargic day after day, dragging not only through runs but the rest of your day, too, something deeper could be going on:<\/p>\n Norris recommends doing an audit: \u201cWhat\u2019s my training load? Am I getting enough recovery? Am I eating enough? Have I done blood work<\/a> recently on these biomarkers?\u201d It can help to check in with a medical provider to talk through the possibilities and what you\u2019ll need to recover. Although some kinds of fatigue you can power through, ongoing low energy is typically a sign that something is off and it needs to be taken seriously.<\/p>\n Want more\u00a0<\/b>Outside<\/i><\/b>\u00a0health stories?\u00a0<\/b>Sign up for the Bodywork newsletter<\/b><\/a>. And for tips on how to train, fuel, and recover better,\u00a0<\/b>sign up for the Sweat Science 101 newsletter<\/b>.<\/b><\/p>\n1. Flat, Heavy Legs<\/h2>\n
How to Fix It: Cut Your Activity Short and Focus on Recovery<\/h3>\n
2. Soreness<\/h2>\n
How to Fix It: Get Sleep and Hydrate<\/h3>\n
3. Burning Muscles<\/h2>\n
How to Fix It: Add Active Recovery into Your Routine<\/b><\/h3>\n
4. Bonking<\/h2>\n
How to Fix It: Consume More Carbs<\/h3>\n
5. Mental Burnout<\/h2>\n
How to Fix It: Mix Up Your Training and Re-shift Focus<\/h3>\n
6. Form Breakdown<\/h2>\n
How to Fix It: Stop Exercising ASAP<\/h3>\n
7. Unrelenting Lethargy<\/h2>\n
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How to Fix It: Check All of Your Vitals<\/h3>\n